/Engine/Plugins/Experimental/ScriptableToolsFramework/Source/ScriptableToolsFramework/Public/ScriptableInteractiveTool.h
The OnGizmoTransformStateChange event fires whenever the user start/ends a Gizmo transform, or when an Undo/Redo event occurs. Note that when Undo/Redo occurs, OnGizmoTransformChanged will also fire. The GizmoIdentifier can be used to disambiguate multiple active Gizmos.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintImplementableEvent, Category="ScriptableTool|Events") void OnGizmoTransformStateChange ( const [FString](API\Runtime\Core\Containers\FString) & GizmoIdentifier, FTransform CurrentTransform, [EScriptableToolGizmoStateChangeType](API\Plugins\ScriptableToolsFramework\EScriptableToolGizmoStateChangeT-) ChangeType )